Blockage in impulse lines of a pressure transmitter may occur because dirt or other material in the process may settle in the impulse line(s) during operation. Typical types of blockages include, for example, solid depositions, wax depositions, hydrate formation, sand plugging, gelling, frozen process fluid plugs, as well as air or foam pockets.
Even when the impulse line or at least one of the impulse lines for a differential pressure transmitter become plugged, the pressure transmitter will generally continue to operate without any indication of the plug. However, the plug can cause erroneous pressure output measurements which can lead to undesired control actions taken by the control operator in the control room responsive to the erroneous pressure measurements. Identifying this error condition is known to generally require manual intervention at the installation site by a service technician. One known automatic plug diagnostic method for a differential pressure transmitter compares a unique noise signature in its output signal obtained during normal process operation with the noise signature of suspected plugged impulse line(s), where the noise in the output signal is known to typically be reduced when the impulse line(s) are plugged.